1. Field of the Invention
The present invention relates to a toner image dryer applied to a wet electrophotographic recording system such as a copying machine and a printer using a liquid developing process, for selectively absorbing only liquid carriers from a development liquid for adjusting transfer conditions.
2. Description of the Related Art
A conventional image printer using wet electrophotographic recording system, has an photosensitive belt (photosensitive body) formed with a photosensitive material, a charger for charging the photosensitive belt, optical exposing unit for forming an electrostatic image on the charged photosensitive belt, development device for forming a toner image by using a development liquid, and transfer and fixing device for transferring the toner image to a recording medium and fixing thereon. Usually, the development liquid used in the development device mainly has toners and liquid carriers for charging toners so as to selectively develop toner grains and dispersing the toners in the development liquid.
In the conventional image printer of this type, it is necessary to selectively absorb the liquid carriers after developing a toner image on photosensitive belt with the development liquid and before transferring the image onto the recording medium. This is because the toner image is set in a filmed state to have a solid component ratio of not less than 95% to thereby adjust transfer conditions.
For absorbing the liquid carriers from the development liquid, a toner image dryer is used in the image printer. Usually, the toner image dryer is provided by a heat roller which contacts on the photosensitive body. The heat roller absorbs the liquid carriers from the photosensitive belt formed with the toner image, and vaporizes from the liquid carriers by heating the roller and diffusing to set in a filmed state to have a solid component ratio of not less than 95%.
But, it is difficult to maintain a balance between absorption and diffusion/vaporization at not more than the heat resisting temperature of the photosensitive belt.
Furthermore, in the conventional roller type drier, image picking due to shearing force at an absorbing and contact part (NIP part) progresses and so does ink contamination in the image drying system accordingly, with the result that it becomes difficult to realize an intended service life.